Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

058
FXUS63 KLOT 231134
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
634 AM CDT Mon Mar 23 2026

.KEY MESSAGES...

- Dry conditions with a warming trend through Thursday.

- Strong cold front will bring another abrupt end to
  unseasonable warmth late Thursday/Thursday evening.

- Thunderstorms are possible Thursday afternoon and evening.

&&

.DISCUSSION...
Issued at 230 AM CDT Mon Mar 23 2026

The large and powerful upper level ridge that`s been responsible
for the recent record demolishing heat continues to be the
dominant feature across the U.S. and is progged to remain so
through the week. Our current chilly weather is a result of a
transient shortwave trough over the Great Lakes and New England,
which caused the mega-upper ridge to retrograde west a bit. A
powerful 160kt+ jet over the eastern Pacific should help push
the upper ridging back eastward toward the Mississippi Valley
over the next few days, which will result in a substantial
warming trend.

Through Wednesday, our weather should be pretty tranquil. Today
will remain seasonably cool with an afternoon lake breeze
keeping temps even chillier close to Lake Michigan. Surface high
pressure will move east of the region and allow southerly winds
to develop and pull in much milder air Tuesday and especially
Wednesday. The proximity of the strong Pacific jet stream looks
to good deal of high level cloudiness on Tuesday and Wednesday,
so didn`t stray from NBM forecast highs. If we end up with more
sunshine, then temps could be several degrees or more warmer
than NBM for highs Tues & Wed.

Thursday`s pattern looks much more like mid-summer than late
March, except for the strength of the mid-upper level flow.
Tightening geopotential heights between an amplifying northern
stream shortwave trough and the powerhouse upper ridge will
result in a strong mid-upper level jet streak developing over
the Great Lakes. At the surface, a fast moving surface low is
expected to race eastward across the region Thursday allowing a
trailing cold front to move southward across in its wake. Not
surprisingly, there is still considerable spread on exact
track of this sfc low and placement/movement of the boundary.
Ahead of the front, strong southwesterly winds should allow for
widespread 80F+ temps again. Currently looks like our southern
CWA will be on the warm side of this front Thursday with less
confidence north of I-80, where spread of potential high temp
outcomes Thursday is very large.

Above the southerly flow at the sfc, there will be a deep
westerly flow aloft which will advect an impressive early
season elevated mixed layer (EML) east into the region. Steep
mid level lapse rates associated with this EML will help bolster
instability, but strong capping at the base of the EML raises
big doubts about whether the cap will be breached in our area.
The strongest synoptic scale ascent looks to be east of our area
by afternoon with frontal forcing not looking terribly strong
either given the veered sfc flow ahead of the front. Question
becomes will surface heating and modest frontal forcing be
enough to break a potentially strong cap, something we may not
have a good handle on until event gets closer. If the cap is
breached, very strong shear and strong instability for late
March would set the stage for severe thunderstorms. Still a lot
of uncertainty this far out, but Thursday will bear watching.

Digging upper trough should allow for another brief, but potent
shot of cold air to spill into the area Friday before temps
slowly moderate heading into next weekend.

- Izzi

&&

.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 634 AM CDT Mon Mar 23 2026

North winds (favoring 340-360 degrees) will continue to gust up
to 20 knots this morning. Winds will veer to around 010 degrees
early in the afternoon while diminishing to 10 to 15 knots,
then veer east with a lake-enhanced boundary around 20Z (for
ORD/MDW). Continued veering of the winds is expected through
tonight, eventually settling SSW prior to sunrise Tuesday.

The back edge of high-end MVFR ceilings will clear the Chicago
terminals within the next hour. Redevelopment of SCT low-end VFR
clouds can be expected later this morning and afternoon,
followed by increasing mid and upper-level clouds tonight into
Tuesday.

Kluber

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 3 PM CDT this afternoon for the IL
     nearshore waters.

     Small Craft Advisory until 9 PM CDT this evening for the IN
     nearshore waters.

&&

$$

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